1. Field of the Invention
The invention relates to fastening methods and systems used for securing posts and the like to mounting surfaces and more particularly relates to post anchoring methods and devices for anchoring wood, fiber or other synthetic composite material posts used in fence, deck, balcony and railing applications to wooden, concrete, fiberglass, vinyl or other surfaces.
2. Description of the Prior Art
There is a need to provide a method and a mechanism by which posts can be secured to generally horizontal surfaces in such a way as to meet or exceed the functional requirements of strength and elimination of rot, and at the same time address aesthetic concerns surrounding the visibility and unsightly nature of the anchoring device and the fasteners used therein.
Strength of design is particularly important for an unsupported run of railing or fence posts that separate areas differing in elevation. Equally important is the need to ensure that the end of the post secured to the surface remains dry so that moisture cannot cause rot that will lead to the eventual degradation and destruction of the post.
Providing a solution to these functional and aesthetic concerns has thus far meant that one is achieved at the expense of the other. Superior strength has heretofore only been achieved with devices requiring a fully visible mechanism and fasteners attached to the exterior of the post. Alternatively, superior aesthetic solutions designed to conceal fasteners have heretofore possessed lower strength characteristics and often require unsightly supporting triangular brackets to stiffen the post to surface connection.
Known devices used to secure posts to concrete foundations, retaining walls and surfaces typically resemble a U shaped bracket with an anchoring appendage protruding from the underside of the bracket that is set into wet concrete. These brackets are painted to inhibit rust and require exterior fasteners to secure the post within it. These types of brackets are functional only and not aesthetically pleasing.
Other common forms of known post anchoring devices possess a square or rectangular metal tube with a molded, forged or welded base. The post fits into the tube and is secured by means of either horizontal fasteners through the sidewalls of the tube into the post, or a bracket, which tightens the circumference of the tube around the post. The base is then secured to the mounting surface with bolts or screws all of which are visible. While functional, these devices are not aesthetically appealing.
One known device that is designed to improve aesthetic appearance is a flat square shaped piece of sheet metal, the perimeter of which is slightly larger than the periphery of the cross section of the post. The metal base is fastened to the bottom of the post by screws or bolts passing through the underside of the base and remains concealed when the post is finally secured. The metal base, now attached to the bottom of the post, is then secured to the mounting surface by bolts or screws, through holes at the corners of the exposed periphery of the base, and remain visible.
This device is an aesthetic improvement from the previous devices. However, the corner fasteners are still visible and the strength of the entire union is dependent upon two factors; the holding power of the screw threads in the end grain of the post; and the shear strength of the screw when the post is subjected to lateral and leverage force.
In addition to the above devices, are a number of patented devices for securing posts to mounting surfaces. For example, U.S. Pat. No. 5,568,909 to Timko, U.S. Pat. No. 5,419,538 to Nicholas et al., U.S. Pat. No. 6,015,138 to Kohlberger et al. and U.S. Pat. No. 4,753,420 to Kaaria disclose devices which can be used to attach and secure posts to mounting surfaces.
Timko discloses a mounting bracket consisting of a square base attached to a square receiving tube similar to the known devices described earlier. The Timko device also has two drainage holes at the base of two opposing walls of the receiving tube. The post is placed in the receiving tube and fasteners are screwed, bolted or nailed through openings in the sidewalls and into the post. The base is bolted or screwed to the mounting surface at its corners. While the Timko device provides a stiff, secure union between post and mounting surface, it is attached to the outside of the post and has numerous visible fasteners that detract from the overall aesthetical appearance.
Nicholas discloses a post fastening system whereby the bottom of the post and the mounting surface must be bored in order to accept two separate discs with a threaded center aperture. The discs are screwed separately into the floor surface and the post. The center aperture receives a threaded stud and the post is then secured to the floor by screwing the exposed end of the threaded stud into the opposing disc. While the Nicholas device conceals the fasteners, boring is required in both the post and the floor surface. The system is designed primarily for newel posts used with interior railing systems. The mounting discs and stud are fitted very shallow into the opposing mating surfaces and therefore the union is not as strong as it would be if the stud were to protrude deeper into the post. It is also unsuitable for outdoor applications because the base of the post would be in direct contact with the mounting surface and subject to moisture and water damage.
Kohlberger discloses a newel post-anchoring device for securing newel posts to concrete and elevate the newel post above the surface to protect it from moisture. Although the device does conceal all fasteners, it is not suitable for mounting on to surfaces that are not as hard as concrete, such as wood, because the base is secured by a wedge bolt that must be placed into a hole bored into concrete or like material. The wedge bolt is specifically designed to provide maximum strength in concrete, thus confining the device's application.
Kaaria discloses a railing system, which includes a post anchor device designed to secure and elevate a wood post to a mounting surface without visible fasteners thereby providing superior aesthetics and keeping the wood from contacting water or moisture. The anchor device has a base plate through the center of which is fitted a lag screw from underneath and protruding vertically. The post is pre-drilled to accept the lag screw and is screwed down onto the plate. This device hides all fasteners, but without bracing, the unsupported newel posts are wobbly because the strength of the post to base connection is dependent upon the integrity of the narrow lag screw. The inherently narrow cross sectional dimensions of the lag screw necessarily means that it can never provide the degree of stiffness that is ultimately required for applications outside of a unitary railing system.
In order for exterior posts to withstand exposure to water and moisture, they should be elevated and not placed in direct contact with the mounting surface. Mounting surfaces may be concrete or the like, wood, fiber glass or other composite materials and therefore the ideal fastening mechanism ought to be suitable for each application. Furthermore, the ideal mechanism ought to hide all visible fasteners to maximize aesthetic appeal and yet still provide strength and stiffness so that a single post, or a plurality of posts forming a unitary run of railing or fencing, can stand without supporting brackets.
Accordingly, there is a need for a post anchoring device and method of using same which can be used on a diversity of mounting surfaces, provide greater structural rigidity and strength, minimize or eliminate exposure to moisture, have high aesthetic appeal by concealing the fastening apparatus, and be easy to install.